So I have a 2015 Silverardo WT, 50k miles, with plow package but no plow or 2nd battery. About 6 months ago, this happened. Triple A came, said battery good... Had towed home. The next day I cleaned all wires in battery area, messed with wires and after trying several times to start, it started! Not 100% sure why though. Now it's happening again... Trying to start, dash goes Black except for service engine orange light, I can hear what appears to be the starter bendix click in, and nothing.. A few seconds later, sounds like the bendix kicks out and the "Service theft Deterrent system" message appears. A few months back I thought the truck was starting to start slow.. So I think I'll try putting in a new battery as others have stated... But i may try crawling under the truck and cleaning the starter terminals first... I'll update on my progress.. Oh and I have an aftermarket remote starter also... At first my dealer said it was that too...